Coronary artery bypass grafting (CABG)
Coronary Artery Bypass Grafting (CABG) is a heart surgery procedure in which one or more blocked coronary arteries are bypassed with a blood vessel graft to restore normal blood flow to the heart muscle. The grafts are usually taken from the patient's chest (thoracic artery), leg (saphenous vein), or forearm (radial artery). The graft creates a new path to divert blood around the blockage and allow it to reach the oxygen-deprived heart muscle, and an estimated 800,000 CABG surgeries are performed worldwide each year.
CABG surgery is used to:
- Restore normal blood flow to the heart muscle
- Relieve the symptoms of coronary artery disease (including chest pain)
- Enable the patient to resume a normal lifestyle
- Lower the risk of a heart attack and other heart problems
- Coronary artery bypass grafting (CABG) is a type of surgery used to improve blood flow to the heart in people with severe coronary artery disease (CAD).
- During CABG, a healthy artery or vein from another part of the body is connected, or grafted, to a blocked coronary artery. The grafted artery or vein bypasses (that is, it goes around) the blocked portion of the coronary artery. This improves the flow of blood and oxygen to your heart muscle.
- CABG is one type of treatment for CAD. Not everyone with CAD needs CABG. In people who are candidates for the surgery, the results are usually excellent, with 85 percent of people having significantly reduced symptoms, less risk for future heart attacks, and a decreased chance of dying within 10 years following the surgery.
- Your doctor will determine if you're a candidate for CABG based on a number of factors, including the presence and severity of CAD. Often nonsurgical treatments, such as medicines and angioplasty, will be tried first.
- Although the surgery is usually done on an elective (scheduled) basis, it may need to be performed in an emergency, such as pending or during a heart attack.
- Although complications are rare, risks of CABG include infection at the incision site, bleeding, reactions to the anesthesia, fever and pain, stroke, heart attack, or even death.
- Recovery may take 6 to 12 weeks or more. Most people can get back to their normal activities about 6 weeks after the surgery.
- Care after surgery may include follow-up visits with doctors, lifestyle changes to prevent further progression of CAD, and taking medicines as prescribed.
Types of Coronary Artery Bypass Grafting
Traditional Coronary Artery Bypass Grafting
This is the most common type of coronary artery bypass grafting (CABG). It's used when at least one major artery needs to be bypassed. During the surgery, the chest bone is opened to access the heart. Medicines are given to stop the heart, and a heart-lung machine is used to keep blood and oxygen moving throughout the body during surgery. This allows the surgeon to operate on a still heart. After surgery, the heart is restarted using mild electric shocks.
Off-Pump Coronary Artery Bypass Grafting
This type of CABG is similar to traditional CABG in that the chest bone is opened to access the heart. However, the heart isn't stopped, and a heart-lung machine isn't used. Off-pump CABG is sometimes called beating heart bypass grafting. This type of surgery may reduce complications that can occur when a heart-lung machine is used, and it may speed up recovery time after surgery.
Minimally Invasive Direct Coronary Artery Bypass Grafting
This surgery is similar to off-pump, but instead of a large incision to open the chest bone, several small incisions are made on the left side of the chest between the ribs. This type of surgery is used mainly for bypassing the vessels in front of the heart. It's a fairly new procedure, which is performed less often than the other types. This type of surgery is not for everybody, especially if more than one or two coronary arteries need to be bypassed.
Why It Is Done
Bypass surgery is usually performed for heart attack only when other treatments, such as medicine and angioplasty with or without stenting, are not useful because of the location or extent of the blockage.
Although new techniques have allowed doctors to use angioplasty and/or stenting increasingly over bypass surgery, some types of heart attack may not be effectively treated with angioplasty with or without stenting. Bypass may be a better option for people with diabetes or with two or more blocked coronary arteries. It may also be a better option when certain areas of the heart are damaged or when angioplasty is not possible for technical reasons.
Who Should Undergo CABG Surgery?
The cardiologist and cardiovascular surgeon work together with the patient and his or her family to determine the best treatment option. Factors they will consider include the extent of the cardiovascular disease, the severity of the symptoms, the patient's age, the patient's health status, and the patient's other medical conditions.
Several types of bypass grafts can be used in CABG surgery. The surgeon decides which graft(s) to use, depending on the location of the blockage, the amount of the blockage, and the size of the patient's coronary arteries.
- Internal mammary arteries or internal thoracic arteries in the chest are the most common bypass grafts used because they have shown the best long-term results. They have their own oxygen-rich blood supply, so in most cases, these arteries can be kept intact at their origin and then sewn to the coronary artery below the blockage. If the surgeon also removes the mammary artery from its origin, it is called a "free" mammary artery. Over the last decade, more than 90% of all CABG patients received at least one internal artery graft.
- The radial artery in the forearm is another commonly used graft. Careful pre- and intraoperative tests determine if the radial artery can be used; if it is, the patient may be required to take a calcium channel blocker medication for several months after surgery to prevent the artery graft from collapsing. Some patients report wrist numbness immediately after surgery, but long-term sensory loss or numbness is uncommon.
- A Saphenous vein from the thigh can be used as a bypass graft. Minimally invasive saphenous vein removal does not require a long incision. One to two incisions are made at the knee, and a small incision is made at the groin, resulting in less scarring and faster recovery.
- The gastroepiploic artery to the stomach and the inferior epigastric artery to the abdominal wall are less commonly used for grafting.
CABG surgery generally lasts from 3 to 5 hours, depending on the number of coronary arteries affected. The cardiovascular anesthesiologist readies the patient for surgery. The surgeon removes the grafts and prepares the arteries for bypassing. Traditional CABG surgery requires a 6- to 8-inch incision down the center of the sternum (breastbone) to provide the surgeon direct access to the heart. To bypass the blockage, the surgeon opens in the diseased coronary artery just below the blockage. If a saphenous vein or radial artery is used, one end is connected to the coronary artery and the other end is connected to the aorta. If a mammary artery is used, one end is connected to the coronary artery and the original end remains attached to the aorta. The graft is sewn into the open coronary artery, redirecting blood flow around this blockage. The procedure is repeated until all affected coronary arteries are treated. It is common for three or four coronary arteries to be bypassed during one surgery.
Heart-Lung Bypass Machine:
During CABG surgery, the heart may need to be stopped during the bypassing procedure to allow the surgeon to sew the new graft(s) securely in place. A perfusionist sets up and monitors the heart-lung bypass machine ("the pump"), which replaces the heart and lungs in circulating blood throughout the body while the heart is stopped.
Off-Pump or Beating Heart Bypass Surgery
Off-pump or beating heart bypass surgery is an option that allows surgeons to perform surgery on the heart while it is still beating. The heart-lung machine is not used, and the heart is not stopped during the procedure. Instead, the surgeon uses advanced operating equipment to stabilize and hold portions of the heart and then bypass the blocked artery in a highly controlled operative environment. Meanwhile, the heart keeps pumping and circulating blood to the body. Some patients are candidates for this option, and some are not. It usually depends on the location and severity of the heart disease.
Minimally Invasive Technique
Minimally invasive coronary artery bypass (MIDCAB) surgery is an option for patients who specifically require a left internal mammary artery (LIMA) bypass graft to the left anterior descending (LAD) coronary artery. Instead of the traditional open-heart incision, a smaller incision through the ribs is used. The benefits of minimally invasive bypass surgery include a smaller incision, a smaller scar, reduced risk of infection, decreased recovery time, and a shorter hospital stay.
After the grafts have been completed during the "on pump" procedure, the heart-lung machine is turned off, the heart resumes beating on its own, and the blood flow returns to normal. Temporary pacing wires and a chest tube to drain fluid are inserted before the sternum is closed with special wires. Then the chest is closed with either internal stitches or traditional external stitches. A temporary pacemaker is sometimes attached to the pacing wires to regulate the heart rhythm if needed. The patient is transferred to an intensive care unit for close monitoring 1 to 2 days after surgery. This includes continuous heart, blood pressure, and oxygen monitoring and frequent checks of vital signs and other parameters. After the patient is transferred to the nursing unit, the hospital stay lasts 3 to 5 more days.
How Well It Works:
Although the immediate risks of coronary artery bypass graft surgery are greater than those of angioplasty, long-term outcomes are similar for both procedures. CABG surgery may offer the advantages of greater durability and more complete revascularization. Generally, the greater the extent of coronary atherosclerosis, the greater the benefits of bypass surgery over angioplasty.
Bypass surgery may be considered a better option for some people who have:
- Disease of the left main coronary artery.
- Weakened heart muscle.
- Valve disease and need surgery.
Bypass surgery often relieves symptoms of chest pain (angina), improves exercise performance, and reduces the risk of a future heart attack.
People with severe coronary artery disease (CAD) have an increased risk of death within a year when they are treated with bypass surgery rather than medicines alone. But 5 to 10 years after bypass surgery, the risk of death from CAD is less for those who had surgery compared with those treated with medicine. Factors that affect these results include the number of coronary arteries that are diseased, the severity of the disease, and the location of the plaque in the coronary arteries.
Full recovery from CABG surgery takes 2 to 3 months. Most patients are able to drive within 3 to 8 weeks. The doctor provides specific and individual recovery guidelines, including instructions for incision care, general health care, activity restriction, cardiac rehabilitation, and return to work after surgery. CABG surgery does not prevent coronary artery disease from recurring; therefore, lifestyle changes and prescribed medications are strongly recommended to reduce this risk.
The most common problem after surgery is the return of chest pain (angina). Severe angina may return shortly after bypass surgery in about 4 out of 100 people. Surgery is usually less successful when it is repeated.
After 5 years, about 4 out of 100 people need another operation. After 10 years, about 12 out of 100 people need another surgery.
Other risks of bypass surgery may include:
- Risks associated with anesthesia.
- Heart attack.
- Excessive bleeding.
- Subtle problems in long-term memory, comprehension, calculation skills, and concentration.